Guitar construction



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GUITAR CONSTRUCTION Filedneo. 22, 195e sheet. 3 of s Fig. 5`

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May13,l1969 MKASH'A I v3,443,465

GUITAR CONSTRUCTION Filed Dec.- 22, 1966 sheet` f of s Michael Kas/ra INVENTOR.

BY wimw'lzfi United States Patent O 3,443,465 GUITAR CONSTRUCTION Michael Kasha, Box 622, Rte. 4, Tallahassee, Fla. 32302 Filed Dec. 22, 1966, Ser. No. 603,905 Int. Cl. Gd 1/08 U.S. Cl. 84-267 20 Claims ABSTRACT OF THE DISCLOSURE This disclosure pertains to a guitar soundboard having an improved elongated bridge mounted in the conventional position on the outer surface thereof and elongated bracing members secured to the inner surface of the lower lobe of the soundboard with the bracing members extending generally longitudinally along the soundboard. The improved bridge and the specific internal bracing utilized coact to free the treble side or end of the bridge and the corresponding portion of the lower lobe of the soundboard for more individual motion excited by the treble strings as compared with motion imparted thereto more fully by the base strings. The internal bracing utilized and the bridge construction used in conjunction therewith serve to individually tune the treble side of the lower lobe of the soundboard to the treble end of the bridge and the base side of the lower lobe of the soundboard to the base end of the bridge for more independent driving of the treble and bass sides of the soundboard by the treble bass ends of the bridge, respectively.

This invention relates to a guitar construction including bridge and soundboard structural features specifically designed to increase the treble brilliance and more elficient driving of the treble and bass sides of the soundboard of the guitar due to impedance matching of the opposite ends of the bridge and the corresponding sections of the soundboard which also results in a louder and fuller tone of the guitar.

Standard classical guitar constructions utilize elongated bridge structures including treble and bass end portions rigidly coupled together for rocking movement and internal elongated bracing members secured to the inner surface of the soundboard which extend beneath the area of the soundboard to which the bridge is secured and therefore tend to transmit both the treble and bass string `vibrations throughout the entire soundboard. While very line classical guitars are produced utilizing this construction, it has been envisioned that reasonably independent excitation of the soundboard by the treble and bass strings would result in more brilliance in the tone of the treble notes. Accordingly, it is the main object of this invention to provide a guitar whose soundboard will more fully independently respond to excitation by the bass and treble strings of the guitar.

Another object of this invention, in accordance with the immediately preceding object, is to provide a guitar construction including features thereof which facilitate independent vibrations of the treble and bass ends of the guitar and the corresponding portions of the guitar soundboard to which the treble and bass ends of the bridge are secured.

A further object of this invention is to provide a guitar bridge construction including treble and bass end portions joined together at adjacent ends by -means of a narrow independent neck portion in the bridge portion centrally intermediate its opposite ends whereby the treble and bass end portions of the bridge may more fully independently rock due to excitation by the treble and bass strings.

Patented May 13, 1969 ICC Still another object of this invention, in accordance with the immediately preceding object, is to provide a guitar soundboard for use in conjunction with the abovementioned divided bridge and which includes elongated bracing members secured to the inner surface of the soundboard and which are interrupted in the regions thereof which pass beneath the area of the soundboard to which the lbridge is secured.

Another object of this invention, in accordance with the immediately preceding object, is to provide elongated bracing members for the inner surface of the soundboard of a guitar constructed in accordance with the preceding object and which are longitudinally tapered in a manner so as to further enhance independent driving of the treble and bass sides of the soundboard by the treble and bass ends of the bridge and tune the treble and bass sides of the soundboard for more responsive excitation by the treble and bass ends of the bridge.

A still further object of this invention is to provide a divided bridge including treble and bass end portions connected by means of a narrow centrally disposed neck portion and which treble and bass end portions are of different maximum width with the treble end portion being narrower than the bass end portion.

A final object of this invention to be specically enu- -merated herein is to provide a guitar construction which will conform to conventional forms of manufacture and which will readily adapt itself to tuning by the guitar maker for substantially complete elimination of dead notes by shifting the enharmonic frequency of the diaphragm relative to the harmonic string frequencies represented by the string-frets.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE l is a front elevational view of a classical guitar constructed in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary sectional view taken substantially upon the plane indicated by section line 2 2 of FIGURE l;

FIGURE 3 is an enlarged fragmentary sectional view taken substantially upon the plane indicated by section line 3 3 of FIGURE l;

FIGURE 4 is an enlarged fragmentary sectional view taken substantially upon the plane indicated by section line 4 4 of FIGURE 2 and illustrating a modified form of bracing;

FIGURE 5 is a fragmentary sectional View taken substantially upon the plane indicated by the section line 5 5 of FIGURE 2;

FIGURE 6 is a fragmentary sectional View taken substantially upon the plane indicated by the section line 6 6 of FIGURE 5;

FIGUR-E 7 is a fragmentary sectional view taken substantially upon the plane indicated by the section line 7 7 of FIGURE 5;

FIGURE 8 is a sectional view similar to FIGURE 5 but illustrating another form of internal bracing for the sound-board of the guitar;

FIGURE 9 is an enlarged fragmentary front elevational view of a guitar soundboard illustrating a divided bridge;

FIGURE 10 is a fragmentary sectional view taken substantially upon the plane indicated by section line 10 10 of FIGURE 9;

FIGURE 11 is an elevational View of the bridge construction illustrated in FIGURE 9 as seen from the lower end of FIGURE 9;

FIGURE 12 is a fragmentary enlarged elevational view of a guitar soundboard illustrating an asymmetrical divided bridge secured to the soundboard;

FIGURE 13 is an elevational view similar to FIGURE 12 Ibut showing a further form of asymmetrical divided bridge; and

FIGURE 14 is a fragmentary sectional view taken substantially upon the plane indicated by section line 14-14 of FIGURE 13.

Referring now more specifically to the drawings the numeral generally designates a classical guitar constructed in accordance with the present invention and including a body generally referred to by the reference numeral 12 of the usual configuration including an upper lobe 14 and a lower lobe 16. The body 12 includes a soundboard or front body panel 18 and a conventional neck referred to in general by the reference numeral 20 extending upwardly from the upper end of the body 12 terminating at its upper end in a conventional head 22 to which the upper ends of the three bass strings 24 and the three treble strings 26 are anchored.

The guitar 10` includes a bridge construction referred to in general by the reference numeral 28 which is secured to the outer surface of the soundboard 18 in substantially centered position on the lower lobe 16 thereof. The bridge construction includes an elongated body 30 whose center portion includes a first outstanding rib 32 grooved as at 34 and a second outstanding rib 36 having six inclined bores 38 formed therein through which the strings of the guitar 10 pass at their ends remote from the head 22. A saddle 40 is Secured in the groove 34 and the strings of the guitar 10 pass over the saddle 40. The body 30 includes a planar undersurface 42 which is abutted on and secured to the outer surface 44 of the soundboard 18.

The bridge construction 28 may be considered as conventional in design and therefore all of the preceding description of the guitar 10 may be considered as exemplary of a conventional guitar.

The lower lobe 16 of the soundboard 18 of the guitar 10 is, however, provided with novel bracing in the form of upper and lower sets of pairs of corresponding upper and lower elongated bracing members 46 and 48 and 50 and 52 secured to the inner surface of the bass and treble sides of the lower lobe 16 of the soundboard 18.

From FIGUR-E 1 of the darwings it may be seen that the bracing members 46 and 48 are disposed in pairs of bracing members 46 and 48 disposed on radii extending from a point 54 at the center of the top of the soundboard 18 and that the lbracing members 50 and 52 are also disposed in pairs of bracing members 50 and 52 disposed along radii extending from the point 54.

The bracing members 50 and 52 include major thickness end portions 56 and minor thickness end portions 58. The bracing members 46 and 48 are similarly formed but are reversed in end to end position relative to the bracing members 50 and 52. In this manner, the minor thickness end portion 58 of the bracing members 50 and 52 are disposed adjacent the area of the soundboard 18 to which the bridge construction 28 is secured while the major thickness end portion 56 of the bracing members `46 and 48 are disposed adjacent the area of the soundboard 18 to which the bridge construction 28 is secured. Therefore, the greater thickness ends of the bracing members 46 and 48 are disposed adjacent the bridge construction 28 on the bass string side of the lobe 16 and the minor thickness end portions of the bracing members 50 and 52 are disposed adjacent the bridge construction 28 on the treble string side of the lobe 16. The lower frequency bass notes are therefore more fully transmitted throughout the bass string side of the lobe 16 while the higher frequency treble notes are effected primarily from the central portion of the treble string side of the lobe 16 of the soundboard 18, this central portion being approximately one-quarter the diameter of the lobe 16. Thus, the lower frequency bass notes are formed by bass note frequency vibration of the entire bass note side of the lower lobe 16 of the soundboard 18 while treble notes are formed by treble note frequency vibration of the treble side of the lobe 16 in a central area thereof encompassing the treble end of the bridge construction 28 and of a diameter approximately one-quarter of the diameter of the lower lobe 16.

The brace or bracing members 46, 48, 50 and 52 include a cross-sectional shape such as that illustrated in FIGURE 4 and which is generally one-half oval. Further, the bracing members are, of course, constructed of lwood and may be suitably shaved throughout their length and especially in the areas thereof ajacent the bridge construction 28 in order to shift the enharmonic frequency of the diaphragm relative to the harmonic string frequencies represented by the string frets of the guitar 10 thus eliminating dead notes which are so frequently encountered even in expensive classical guitars.

In the classical Spanish guitar, especially the Torres design, the sound bars or bracing members extend completely across the area of the soundboard to which the bridge construction is secured. Thus, the rigid bridge construction is securely fastened to the soundboard and the latter is rigidified to the extent that the higher frequency treble note vibrations are forced to drive the entire correspending side of the soundboard, The size of this area of the soundboard and its rigid construction prevents the treble strings from properly exciting the soundboard in a manner to achieve brilliant treble notes.

The vibrations of the diaphragm or soundboard of the guitar top panel require that the normal modes of motion be freely excited. Some of these normal modes of motion are selectively excited with highest amplitude by a rocking bridge and the conventional design of undivided sound bars or bracing members extending completely beneath the area of the soundboard to which the bridge construction is secured prevents these normal modes of motion to be excited freely whereas the use of divided sound bars or bracing members such as bracing members 46, 48, 50 and 52 enables the most ellcient excitation of the soundboard with the greatest possible amplitude.

Using the Bessel Function Solution for frequency of circular plate normal mode of motion with appropriate boundary conditions, a template contour for free treble frequency oscillation of the soundboard was approximated as one-quarter D where D is the approximate soundboard diameter. This portion of the soundboard of the guitar of the instant invention is left free of bracing in the treble region of the bridge and enables the soundboard to be tuned by the maker of the guitar.

The bracing members 46, 48, 50 and 52 are arranged in fan-like position relative to each other and, except for being divided in the region of the soundboard 118 to which the bridge construction 28 is secured, are generally conventional in design. However, with attention now directed more specifically to FIGURES 5-8 of the drawings, it may be seen that in addition to a fan-like arrangement of bracing members an arrangement which might best be termed radial bracing can also be employed, see FIGURE 8, radial bracing being utilized to gain even greater eiciency in exciting the soundboard.

In FIGURE 5 of the drawings there is illustrated a modified form of fan bracing including bracing members 46', 48', 50 and 52 which are similar to bracing members 46, 48, 50 and 52, The bracing members 46-52 are trimmed at the. ends thereof adjacent the center of the lower lobe 16 of the soundboard 18 along an asymmetrical contour line 60 which forms a boundary for an area of the soundboard 18 to Whose outer surface an asymmetrical bridge construction generally referred to by the reference numeral 62 is secured. The left side of the area bound by the contour line 60 is larger than the right side and is of a diameter approximately one-quarter of the diameter of the lobe 16 and is positioned on the treble string side of the soundboard 18. Although the bracing members 46-52 are trimmed exactly along the contour line 60, such exact trimming is not required but should only be approximate and may be varied as desired so as to shift the enharmonic frequency of the soundboard relative to the harmonic string frequencies represented by the string frets of the guitar as previously set forth. Further, it will be noted that the bracing members 46-52 are arranged in only five pairs of bracing members whereas the :bracing members 46-52 include seven pairs of bracing members, the number of pairs of bracing members not being a crucial factor but a matter of preference by the guitar maker.

With attention now directed more specifically to FIG- URE 8 of the drawings there may be seen a further modified form of bracing construction which includes pairs of `bracing members 46" and 48 and 50" and 52T corresponding to the bracing members 46-52 but which are arranged in a radial pattern radiating generally outwardly from the center of the lower lobe 16 of the soundboard 18. In addition, the bracing assembly illustrated in FIG- URE 8 further includes a pair of transversely extending opposite side bracing members 64 and 66 and a center transversely extending bracing member 68. The bracing construction illustrated in FIGURE 8 of the drawings may be utilized in conjunction with the asymmetrical bridge 62 previously referred to and it has been found that the radial Ibracing arrangement illustrated in FIGURE 8 of the drawings further enhances greater eiciency in exciting the soundboard 18 over the fan-type bracing construction illustrated in FIGURE 5. The bracing members 46"-52 are contoured generally in the same manner as the bracing members 46'52 are contoured. The brace members 46 include major width end portions 70 adjacent the area bound by the contour line 60 and minor thickness end portions 72 remote from the contour line 60. On the other hand, the brace members 50 and 52 include major thickness end portions 74 remote from the contour line 60 and minor thickness end portions 76 adjacent the contour line 60.

With reference now more specifically to FIGURE 9 of the drawings there may be seen a modified form of divided classical bridge construction generally referred to by the reference numeral 78 and which is substantially identical to the bridge construction 28 except that it includes opposite end portions 80 and 82 for supporting the base and treble strings 24 and 26, respectively. The opposite end portions 80 and 82 are interconnected by means of an integral slim neck portion 84 extending therebetween and accordingly, the end portions 80 and 8-2 may rock independently of each other. Further in FIG- URE 12 the bridge construction 62 may be seen in more detail as including end portions 86 and 88 corresponding to the end portions 80 and 82 but which are generally elliptical on the part of the end portion 86 and elongated tapering wedge-shaped on the part of the end portion 88'. The end portions 86 and 88 are also interconnected by means of an integral slim neck portion 90 and the end portions 86 and 88 may therefore also rock substantially independently of each other.

In FIGURES 13 and 14 there is still another asymmetrical bridge construction illustrated which is generally designated by the reference numeral 91 and which includes a large fan shaped end portion 92 and a narrow thin and tapering wedge-shaped end portion 94, the end portions 92 and 94 being interconnected by means of a narrow neck portion 96 corresponding to the neck portions 84 and 90.

The end portions 8-0 and 82 are uniform in width throughout substantially their entire length whereas the end portions 86 and 92 of the bridge construction l62 and 91 are considerably wider than the end portions 88 and 94. The end portions 82, 88 and 94 are of course, those end portions which support the treble strings 26 of the guitar whereas the end portions 80, 86 and 92 support the bass strings 24. The slower vibratory or rocking movement of the greater thickness end portions 86 and 92 combine with the major thickness end portions of the associated brace members carried by the undersurface of the bass string side of the lower lobe of the soundboard 18 to enable the bass strings 24, through the bass string side of the bridge constructions 62 and 91, to drive substantially the entire bass string side of the lobe 16. However, the thinness of the end portions 88 and 94 of the bridge constructions 62 and 91 combines with the minor thickness end portions of the associated bracing members to enable only those portions of the treble string side of the lower lobe 16 immediately adjacent the bridge constructions 62 and 91 to be effectively driven by the treble strings 26 of the guitar 10 and therefore this smaller area of the soundboard 18 responds with more brilliance to the treble notes of the guitar 1t).

In summary, the divided pairs of bracing members of the various bracing constructions disclosed and described herein enable a large portion of the bass string side of the soundboard 18 to be `driven by the bass strings of the guitar and only a smaller portion of the treble string side of the soundboard 18 of the guitar 10 to be effectively driven by the treble strings. Further, the divided feature of the bridge constructions 78, 62 and 91 enables the opposite end portions of these bridge constructions to rock substantially independently of each other and to therefore more effectively independently drive the bass and treble string sides of the soundboard 18. Further, the asymmetrical congurations of the bridge constructions 62 and 91 render these bridge constructions more effective to drive the bass and treble string sides of the soundboard 18'.

Accordingly, each of the three above set forth features of applicants invention represents an improvement over undivided bracing, undivided bridges and symmetrical bridge configuration. However, the combination of any two or all of these three features also represents an improvement.

In addition, the utilization of radial bracing such as that illustrated in FIGURE 8 of the drawings as opposed to more conventional fan bracing such as that illustrated in FIGURES l and 5 of the drawings constitutes a further refinement of the instant invention.

What is claimed as new is as follows:

1. In combination, a generally planar guitar soundboard including bass and treble string sides on opposite sides of a first plane extending longitudinally of and disposed generally normal to said board, an elongated bridge construction extending transversely of said board and secured to the outer surface thereof, a first end portion of said bridge being adapted to support the bass strings of the associated guitar and a second end portion of said bridge being adapted to support the treble strings of the guitar, said end portions being disposed on opposite sides of said plane, and a plurality of sets elongated laterally spaced and longitudinally extending bracing members secured to the undersurface of said board and extending generally longitudinally of the latter, said bridge construction being disposed in a second plane disposed generally normal to said first plane, said sets of bracing members 'being `disposed on opposite sides of said second plane and including adjacent end portions adjacent but terminating spaced distances from said second plane.

2. The combination of claim 1 wherein said bridge includes a narrow longitudinally short center portion interconnecting said first and second end portions and providing for substantially independent rocking of said end portions and thus individual excitation of associated portions of said board by the bass and treble strings.

3. The combination of claim 1 wherein said bracing members disposed on opposite sides of the second end portion of said bridge have their ends adjacent said second en-d portion .terminating generally along a contour line scribing a circle in which said second end portion is disposed and generally centered longitudinally of said board and of a diameter approximatetly one-quarter the transverse width of said soundboard.

4. The combination of claim 3 wherein said bracing members are disposed generally in pairs of bracing members disposed on opposite sides of said second plane and along radii of the intersection of the top end of said board and said iirst plane.

5. The combination of claim 4 wherein the bracing members spaced from and disposed on opposite sides of said iirst plane include major thickness end portions adjacent said second plane on the bass string side of first plane and minor thickness end portions adjacent said second plane on the treble string side of said second plane.

6. The combination of claim 1 wherein the bracing members on opposite sides of said second plane include divergent end portions remote from said bridge.

7. The combination of claim 6 wherein said sound board includes a pair of opposite side elongated and transversely extending bracing members secured to the undersnrface of said board and including adjacent end portions spaced outwardly of the opposite ends of said bridge.

8. The combination of claim 7 including a center elongated transversely extending bracing member secured to the undersurface of said board beneath said bridge and including opposite end portions spaced inwardly of the opposite ends of said bridge.

9. The combination of claim 1 wherein said bridge is of generally constant width throughout substantially its entire length.

10. In combination, a generally planar guitar soundboard including base and treble string sides on opposite sides of a iirst plane extending longitudinally of and disposed generally normal to said board, an elongated bridge construction extending transversely of said board and secured to the outer surface thereof, a first end portion of said bridge being adapted to support the bass strings of the associated guitar and a second end portion of said bridge being adapted to support the treble strings of the guitar, said end portions being disposed on opposite sides of said plane, and said ibridge being disposed in a second plane disposed generally normal to said first plane, said bridge including a narrow longitudinally short center portion interconnecting said first and second end portions against free annular displacement relative to each other in a plane paralleling said soundboard while providing for substantially independent rocking of said end portions through said plane paralleling said board and thus individual excitation of associated portions of said hoard by thel bass and treble strings.

11. The combination of claim 10 wherein said center portion is stiff and therefore positively connects said rst and second end portions.

12. The combination of claim 11 wherein said center portion forms an integral portion of said iirst and second end portions.

13. The combination of claim 10 wherein said first and second end portions are of substantially constant width throughout major portions of their length.

14. In combination, a generally planar guitar soundboard including base and treble string sides on opposite sides of the iirst plane extending longitudinally of and disposed generally normal to said board, an elongated bridge construction extending transversely of said board and secured to the outer surface thereof, a rst end portion of said bridge being adapted to support the bass strings of the associated guitar and a second end portion of said bridge being adapted to support the treble strings of the guitar, said end portions being disposed on opposite sides of said plane, and said bridge being disposed in a second plane disposed generally normal to said first plane, said bridge including a narrow longitudinally short center portion interconnecting said first and second end portions providing for substantially independent ,rocking of said end portions and thus individual excitation of associated portions of said board by the bass and treble strings, said iirst end portion being of a width greater than said second end portion.

`15. The combination of claim 14 wherein said iirst end portion gradually increases in width toward the end thereof remote from said second end portion and the latter tapers in width toward the end thereof remote from said first end portion.

16. The combination of claim 14 wherein said iirst end portion is generally eliptical in plan with its major axis extending longitudinally of said bridge and said second end portion being generally wedge-shaped in plan with its minor width end rounded.

17. The combination of claim 14 including a plurality of sets of elongated laterally spaced and longitudinally extending bracing members secured to the undersurface of said board and extending generally longitudinally of the latter, said sets of bracing members being disposed on opposite sides of said second plane and the bracing members of said sets disposed on opposite sides of the second end portion of said bridge having their ends adpacent said second end portion terminating generally along a contour line scribing a circle in which said second end portion is disposed and generally centered longitudinally of said board and of a diameter approximately one-quarter the transverse width of said soundboard.

18. The combination of claim 17 wherein said bracing members of said sets of members are disposed generally in pairs of bracing members disposed on opposite sides of said second plane and along radii of the intersection of the top end of said board and said iirst plane.

19. The combination of claim 17 wherein the bracing members on opposite sides of said second plane include divergent end portions remote from said bridge.

20. The combination of claim 19 wherein said bracing members disposed on opposite sides of the iirst end portion of said bridge have their ends adjacent said first end portion terminating a spaced distance from the latter.

References Cited UNITED STATES PATENTS 659,330 10/1902 Tapley 84-307 FOREIGN PATENTS 622,735 3/ 1927 France.

RICHARD B. WILKINSON, Primary Examiner.

I. F. GONZALES, Assistant Examiner.

U.S. C1. X.R. 

